two reasons:
- I have a little bit more followers (a lot of programmers), so if I resteem, than this goes directly to your target group :)
- I think after some time in social media and on steemit I can recognize what has a potential to become more popular on steemit.

but the most important thing is, that you produce awesome content, so this is just a natural consequence of your work ;) If i would not do that, for sure someone else would do that a little bit later ;)